1. Field of the Invention
The present invention relates to a data generating method, an information processing apparatus achieving the data generating method, and an information processing system including the information processing apparatus.
2. Description of the Related Art
Recently, software develops at a rapid pace as computer hardware advances. The amount of data required to achieve an application program reaches several gigabytes to several tens of gigabytes, for instance. Some of such software may require an update after its release. Here, the updating is done for the purpose of adding data or functions and correcting or modifying a program, for instance.
When a certain data file is updated so as to generate another data file with updated content, it is generally practiced that the updated data file is sent to replace the data file before the update. However, in many cases, the updated data file is much correlated with the original data file (the data file before the update) and therefore the difference between the data file before the update and the updated data file is small. Accordingly, the delivery cost can be reduced if a difference file can be prepared and an updated data file can be produced, at a destination, from the data file before the update and the difference data file.
At the same, there may be cases where the data files before and after the update are encrypted and signed from the viewpoint of security and the like. In such a case, there is little correlation between the data file before the update and the updated one. Thus, the difference cannot be reduced even if the difference only is delivered. Note that the delivery cost must always be taken into consideration when the updated data files are to be transmitted. Transmitting and receiving the data take some extra time if the updated data whose data amount is large is to be sent in its entirety at once. Also, the communication cost for the transmission and receiving of data may increase depending on a user's communication environment.